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Title: Radioastron studies of the nearby, turbulent interstellar plasma with the longest space-ground interferometer baseline

RadioAstron space-ground very long baseline interferometry observations of the pulsar B0950+08, conducted with the 10 m Space Radio Telescope in conjunction with the Arecibo 300 m telescope and the Westerbork Synthesis Radio Telescope at a frequency of 324 MHz were analyzed in order to investigate plasma inhomogeneities in the direction of this nearby pulsar. The observations were conducted at a spacecraft distance of 330,000 km, resulting in a projected baseline of 220,000 km, providing the greatest angular resolution ever achieved at meter wavelengths. Our analysis is based on fundamental behavior of structure and coherence functions. We find that the pulsar shows scintillation on two frequency scales, both much less than the observing frequency, but modulation is less than 100%. We infer that the scattering is weak, but a refracting wedge disperses the scintillation pattern. The refraction angle of this 'cosmic prism' is measured as θ{sub 0} = 1.1-4.4 mas, with the refraction direction being approximately perpendicular to the observer velocity. We show that the observed parameters of scintillation effects indicate that two plasma layers lie along the line of sight to the pulsar, at distances of 4.4-16.4 pc and 26-170 pc, and traveling in different directions relative to the linemore » of sight. Spectra of turbulence for the two layers are found to follow a power law with the indices γ{sub 1} = γ{sub 2} = 3.00 ± 0.08, significantly different from the index expected for a Kolmogorov spectrum of turbulence, γ = 11/3.« less
Authors:
;  [1] ; ; ; ; ; ;  [2] ; ;  [3] ; ; ; ;  [4] ;  [5] ;  [6] ;  [7]
  1. Pushchino Radio Astronomy Observatory, Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Pushchino, Moscow Oblast' 142290 (Russian Federation)
  2. Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Profsoyuznaya str.84/32, Moscow 117997 (Russian Federation)
  3. Department of Physics, University of California, Santa Barbara, CA 93106 (United States)
  4. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
  5. York University, Department of Physics and Astronomy, 4700 Keele Street, Toronto, Ontario M3J 1P3 (Canada)
  6. The Netherlands Institute for Radio Astronomy (ASTRON), Dwingeloo (Netherlands)
  7. National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411007 (India)
Publication Date:
OSTI Identifier:
22356925
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 786; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; APPROXIMATIONS; INTERFEROMETERS; INTERFEROMETRY; INTERSTELLAR SPACE; LAYERS; MHZ RANGE; MODULATION; PLASMA; PULSARS; RADIO TELESCOPES; REFRACTION; RESOLUTION; SCATTERING; SCINTILLATIONS; SPACE; SPECTRA; SYNTHESIS; TURBULENCE; WAVELENGTHS